Ntaganda walked up to the embassy gates at 7.30am on Monday to turn himself in and request that he be handed over to the international criminal court (ICC).

The move was an uncharacteristic white flag from a man who has long been an agent of chaos in the east of the Democratic Republic of the Congo, allegedly responsible for murder, rape, recruiting child soldiers and sexual slavery.

The fall of the general – a man who "kills people easily" claimed one witness – came after his own rebel movement turned against him and he lost the patronage of neighbouring Rwanda.

Until recently Ntaganda was able to move about eastern Congo, playing tennis and cocking a snook at the ICC, but this personification of impunity now faces a long sentence behind bars.

Nicknamed the Terminator and just over 6ft tall, Ntaganda appears a youthful, smooth-cheeked, figure. He was often shown in photographs smiling broadly, wearing military berets or leather cowboy hats with camouflage fatigues. He was born in Rwanda in 1973, moved to Congo as a teenager and spent his life fighting, sometimes on the side of government, sometimes as a rebel, in the region's endlessly shifting alliances.

The events that swept him out of his hiding place in the bush and into the hands of American officials in Kigali were swift and brutal, though the details remain murky.

Ntaganda and Sultani Makenga, the movement's two leaders, never saw eye to eye. Ntaganda feared Makenga would sign a peace agreement and hand him over to Congolese authorities or even kill him.

Ntaganda attempted to arrest Makenga, and two factions emerged. Within days deadly internecine fighting forced Ntaganda loyalists to go to the southern part of M23 territory and Makenga's men to go to the north.

Makenga, reported to have been negotiating a peace deal with the Congolese government, began attacks on Ntaganda's smaller band of fighters. By the weekend Ntaganda loyalists were fleeing into Rwanda.

Ntaganda's whereabouts remained a mystery until he stunned observers by handing himself in at the US embassy in Kigali on Monday.

His request to be transferred to the Hague surprised many. However, he has made many powerful enemies in Kigali and Kinshasa; for him international justice was probably preferable to the consequences of handing himself over to Congolese or Rwandan authorities, or staying on the run. He had nowhere else to go.

"He must have been so afraid for his life that a long prison sentence in the Hague looked like his best option," said Jason Stearns, a political analyst who specialises in Congo. "He must have been pretty scared."

The US is not a signatory to the Rome statute so is not obliged to hand Ntaganda over to the ICC; however the court has expressed confidence that it will comply.

Ntaganda's trial could prove embarrassing for Rwanda, which has been accused of having a hand in three rebellions in eastern Congo since 2002, all of which featured Ntaganda as a key player.

Stearns said: "This surrender marks his fall from favour with the Rwandan government. He had become a liability because of his notoriety. He's a reliable general but he's also a thug. The Rwandans realised that it was better to let M23 implode and see who came out of it."

There was little mention of Rwandan meddling when Ntaganda's co-accused, Thomas Lubanga, was found guilty of the war crime of recruiting and using child soldiers in the ICC's first case. But Stearns said: "There's a lot of will in the prosecution to push that line. There is going to be a great effort to highlight outside complicity in the crimes he is accused of."

The capture of Ntaganda will come as a timely boost for the ICC, which was recently embarrassed when the indicted Kenyan presidential candidate Uhuru Kenyatta emerged victorious in recent elections.

Ntaganda has been wanted since 2006 for conscripting and using child soldiers during a 2002-03 conflict in the eastern Ituri province. A second arrest warrant, issued last July, accused him of a range of crimes including murder and rape.

But for a long time Ntaganda was untouchable. He was elevated to the rank of general in a 2009 peace deal between the Congolese government and M23's predecessor, the National Congress for the Defence of the People. Between 2009 and 2012 Ntaganda was the highest-ranking army officer in the east; his freedom was considered central to the fragile peace reigning in Congo's restive Kivu provinces.

With an arrest warrant hanging over his head, Ntaganda ate in the finest restaurants in Goma, the capital of North Kivu, and played tennis at the most luxurious hotel in town.

But last April Congo's government called for his arrest, spurring the latest uprising in the east.

Reports that Ntaganda was leading M23 were repeatedly denied by the rebel leadership throughout the insurrection, which the UN said was backed by Rwanda.

Following the rupture, Makenga's faction began speaking about the presence of Ntaganda, but insisting that his influence had been unknown to them up until that point. They claimed that the former political leader of the unified M23 movement, Jean Marie Runiga, a bishop, had been secretly working with Ntaganda.

"We always knew that [Ntaganda] was with Runiga," said Colonel Fred Nganzi, after Ntaganda's surrender. "These events are a move towards peace, but why did [Ntaganda] take so long to hand himself over to justice?"

The peace process now seems likely to advance. Congolese army sources suggested the capture or killing of Ntaganda had been a government-imposed prerequisite to any deal.

When asked whether a peace deal was possible, Nganzi said, "it is if Kabila wants it", referring to the president of DR Congo.

On Tuesday, in Ituri district – the scene of Ntaganda's alleged crimes in the ICC's first case – people were delighted with the news.

"I was so happy when [Ntaganda] surrendered," said Prince Fala, a part-time student selling phone credit from a wooden booth in the district capital, Bunia. "This will put an end to the war with M23. As long as the Americans hand him over to the ICC, that will calm our worries. The war in Congo concerns every tribe; it doesn't matter if you are Lendu, Hema, Tutsi or Hutu. Everyone is happy he has surrendered."